Process of recovering alkali metal sulphites from fusion liquors



Jan. 13, 1931-. c. L. MASTERS 1,788,955

PROCESS OF RECOVERING ALKALI METAL SULPHITES FROM FUSION LIQUORS Filed June 4, 1927 Patented Jan. 13, 1931 ommen curr". museums; csr-Nima', wrsrvmerma, Assioma; nrrnnsnrlnssrennnms;anni nrxo Garmont-commun; eonronarronnrwnsrvraermni.

'rnocrsslorf'ancovnnme'muren sunrnirnsfmeivfirusron menons' My; invention relates.. particularly tofthefv recovery of sulphitesbfY thefalkali metalst fromfusionfliquors obtained. in- .the productionfophenolie compounds.;

The-.object of' my yinvention isf toprovideraprocess for thefreeoveryfof alkalimetalwsulephites from fusion liquors obtainedfinf-the produetion of plienolie` compoundsfas; for

example, suehf as'areobtained-iinlthepro duc-4 tion of. phenol onbetafnaphtlrol..

Itisfwellzknowmthat phenolic compounds; arerfprodced by the-fuse. of .organicwallali metalsul'phonatesf with alkali vmetal hydroX'f idesf'a'ccording :to the following reaction username-Hs.

Certain-methods' arelknown by; Whioh-'the phenolicfcompounds r may!v beseparatedw from.` thefffu'sionfproduetcontainingvanfexeess fof alkali,r forf'exainplerby-fthefaddition oian'acid tothe =ffusion= product, f whichy has been pref-f viensly dissolved',for eXample, inaccord-u aneefwithf `the following? reaction: ROMr-tMzSQsrrMeOHfrRiso@ t I Y i In''aceordance Wvithmy 'processffI uti'lizensul.- phu-rfdioxide rior. this-purpose; thus: .produc-lingthe: Vfree'rphenolic. compound -I and'y an'v al'- kali metalc fsulphite, andravoiding contamilf nation.-`4 Withfundesirable: solids which lwould. be formed by the use of otlnerracidsJ-vv The sulphu'idioxide :usedf for thispurposemay bef obtained as :a by-produet in the-r manufacrturingfprocess used for the. production off RoneaeMasoB-wnzo s'u-lpbona'te with.: an.- allaliHneta-ll hydroxide",V with sulphurdioxi'deyffand fromfwhioh the! greater part-f of." the phenolic` product'- liasbe'enfr removed.- by separation,decantation, etc.. 'Ehe Yselutifonf-thus obtained. may,l be.r passed .-through'. a kvheat exchanger* and.- theng is..preferably conducted towa: stripping; colf umn The' steam v for thefstripping column isf-obtained. froml any suitable source but: p re'ferjalolyf=y fromf a:y pressure-j evaporator in. which fthe. residual i'liquors.- from: the.:7 subse` quent* alkali meta-lsulphite crystallition f. are' concentrated ffor 'furthery recovery 'o-lthefsulphitetherefrom.-l Thefsulphite'liquors, thus;- having; been freed from-.fthe phenolic com-- po'undsby .thestrippingcolumn, are L'filtered toremove:v theiinsoluble impurities ande then conveyed tela.crystallizing.,apparatus-for the removal ofaflarge percentage oi'thesulphite,"-;after 'Whichthefresidu-all vliquors are conveyed.; back' to fthe-v pressure?" evaporator inthe .mannergde'sorib'edu A Vh'ilefmyf 'inventionds capable .of being carried; out iii-manyy difrent'Ways,r for the` purpose, offillustrati-on vI- shallv describe only certain Waysfof! carrying-'out the :samefherematter-5 :and .While it isY `capa-blefof beingl lcar*-l ried. out-in. connectionlfvvith*` many diierent' types-ofapparatus, Iff'h'ave shownzonly one. typeofapp arat'us l-in-eo'nneotion' therewith `in thefaecompanyingdrawings, `in Whiehl-y .The igurefis a diagrammatic` representation. offpan* apparatus which may 'be' vused-iin accordance :With my Y invention; f Y

For example; in? carryingout'myinvention, .in the'case Wherefusion-liquors are. used; resulting.` from? the production ofVY phenol,l I start with the-fusion :liquor obtained from `the fusion of' an organic-alkali:metal sulphonate with Ysodiiirtr.hydroxide-.and the product of which fusiomaft`er the fmajorl portion of' the phenol producedhas-been removed-by decantation orfotlervs'fise,l has sbeen t subjected to .the aetion'off sulphur dioxide.: The-'liquid thus obtained islsuppliedt byy alpipe 1f to, a,.-pre. heater.Zwhioh:isrpreheatedfby-means of a our: rent ofstea-m supplied by'l an inletfpipef, and whichV isexhausted through an: outlet pipe. .4. 'IlhisvYpreheated` stea-xnE is. `supplied vfrom a sourcewhich.-wilL-bevhlereinater described;A

From the preheater 2' the liquid is conveyed by a pipe 5 to a stripping column 6 filled with Raschig rings or other filling material, or which may be a distilling column constructed in any other desired manner. In the column 6 the said liquid passes countercurrent to an upwardly flowing current of steam supplied through a pipe 7 entering the bottoml of the column 6 and exhausted from the top of the column by a pipe 8 leading to any other suitable point for further use, if desired. vIn the course of the treatment of the liquid in the column 6 the phenol is entirely removed and the resultant liquid passes out of the bottom of the column 6 by means of a pipe 9 and thence to a pump 10 from which it is delivered by a pipe 11 to a liquor storage tank 12 provided with Lan agitator 13 driven from any suitable source of power. From this tank the liquor passesofin by a pipe 14 toY a pump 15 by which it is delivered'througb a pipe 16 to a filter 17 to removeV any solid impurities. From this point the'liquor is delivered by a pipe 18 to a tank 19 provided for receiving the ltered sulphite solution. The solution then passes by means of a valved pipe 20, which may contain a'pump 20a, to a precooler 21 cooled in the manner hereinafter described. From the precooler the liquid containing some crystals passes out by a pipe 22 to a mechanical crystallizer 23 which is cooled by a current of any desired kind of refrigerant, supplied by an inlet 24 and carried off by an outlet pipe 25, which is adapted toV pass through a jacket in the form of a series of chambers 26 locatedV around the mechanical crystallizer. The overflow from this crystallizer 23 is discharged by a pipe 27 into a settling tank 28 from which the crystals of alkalimetal sulphite separate out and are conveyed away by a valved pipe 29 to avcentrifuge not shown, or any other suitable means for recovering the crystals from the liquid carried thereby. 'The supernatant liquor passes away from the tank 28 by a pipe 30 to a sump 31 and thence toa pipe 32 from which the liquid is deliveredv at a temperature of approximately 0"4 C. bya pipe 33 to a jacket in the form of a series of chambers 34 contained around the precooler 21, from which jacket the liquor passes out by a pipe 35 to a weak sulphite liquor storage tank 36. A pipe 37, having a pumpf38 therein, withdraws the weak sulphite liquortherefrom and deliversv the same by a pipe 39 to a heat-exchanger 40 supplied witlisteam as hereinafter described, from which the liquor is delivered by a pipe 41 to apressure evaporator 42, from the top of which steam, at anyv desired pressure, is delivered by a pipe 43 having valved branches 7, 3 and 44. The valved branch pipe 44 is connected to the preheater 40, which has a discharge pipe 45 for the condensed steam.

In the pressure evaporator, furthermore, there is a supply pipeV 46 for boiler steam `chamber 52 from which the concentrated sulphite liquor may be delivered bya valved outlet pipe 53'to the pipe 20.

It will be understood that my process may be carried out, also, with other phenolic compounds instead of the phenol just described, as, for example, beta naphthol.

While I have described my invention above indetail I wish it to beunderstood that many changes may be made therein without departing from the spirit 1. The process of recovering an alkali metal sulphite from phenolic solutions containing the same 'which comprises removing the phenolic compound from vsaid 'solution by distillation mean-s, filtering the residual solution, cooling the filtered solution sufficient to crystallize therefrom the greaterV portion of the sulphite content, separating the crystals of alkali metal sulphite from the cooled solution, concentrating the residual solution by heating means and adding the concentrated solution to the said filtered solution.

2. 'Ihe process of recovering an alkali metal sulphite from phenolic solutions containing the same which comprises removing the phenolic compound from said solution by distillation means, filtering the residual solution,

of the same.

cooling the filtered solution, further cooling the said solution by 'refrigerating means, separating the crystals'of alkali metal sulphite from the cold solution, passing the cold solution in heateXchang'e relationship with the said filtered solution,concentrating the residual'solution by heating means, and adding the concentrated solution to the said filtered solution.`

3. The process of recovering an alkali metal sulphite from phenolic solutions containing the same which'Y comprises removing the phenolic compound from said solution by distillation means, cooling the residual solution to a temperature at which crystallization of the alkali sulphite takes place, and separating the crystals from the cooled solution.

"4. The process of recovering sodium sul-v phite from a phenol 'solution containing the same which comprises removing phenol from said solution by distillation means, filtering the residual solution, cooling the filtered solution suiicient to crystallize therefrom the greater'portionI of the sodium sulphitecontent, separating the` crystals ofsodium sulphite from the cooled solution, concentrating the residual solution by heating means, and adding the concentrated solution to the said filtered solution.

5. The process of recovering sodium sulphite from a phenol solution containing the same which comprises removing phenol from said solution by distillation means, filtering the residual solution, cooling the filtered solution, further cooling said solution to approximately Oo C. by refrigerating means, separating the crystals of sodium sulphite from the cold solution, passing the cold solution in heat exchange relationship With said filtered solution, concentrating the residual solution by heating means and adding the concentrated solution to the said filtered solution.

6. The process of recovering sodium sulphite from a phenol solution containing the same Which comprises removing the phenol from said solution by distillation With steam, cooling the residual s olution to a temperature of approximately 0 C. and separating the sodium sulphite crystals from the cooled solution.

In testimony that I claim the foregoing, I have hereunto set my hand this 22nd day of February, 1927.

CARL L. MASTERS. 

